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An efficient synthetic route toward the highly congested [5-6-7] tricyclic core of calyciphylline A-type alkaloids has been developed. This approach features a highly efficient intramolecular Diels-Alder cycloaddition to establish the aza-five-membered C ring as well as the C1 all-carbon quaternary center, and a subsequent cyclopropanation together with a ring-expansion reaction of the resulted adduct to construct the seven-membered D ring. [ABSTRACT FROM AUTHOR]

A fused 6,6,5-tricyclic difluorinated nicotine analogue was efficiently assembled in five steps in 36% overall yield. The conformation-restricting unit is a six-membered fluorinated carbocycle. The gem-difluoromethylene group was introduced through an indium-promoted Barbier allylation of 3-bromo-3,3-difluoropropene. The construction of the tricyclic skeleton was achieved using an intramolecular azomethine ylide-alkene [3+2] cycloaddition. [ABSTRACT FROM AUTHOR]

Lipids are key factors in nutrition, structural function, metabolic features, and other biological functions. In this study, the lipids from the heads of four species of shrimp (Fenneropenaeus chinensis (FC), Penaeus japonicus (PJ), Penaeus vannamei (PV), and Procambarus clarkia (PCC)) were compared and characterized based on UPLC–Q–Exactive Orbitrap/MS. We compared the differences in lipid composition of four kinds of shrimp head using multivariate analysis. In addition, a zebrafish model was used to evaluate pro-angiogenic, anti-inflammatory, anti-thrombotic, and cardioprotective activities of the shrimp head lipids. The lipids from the four kinds of shrimp head had different degrees of pro-angiogenic activities, and the activities of PCC and PJ shrimp lipids were more significant than those of the other two species. Four lipid groups displayed strong anti-inflammatory activities. For antithrombotic activity, only PCC (25 μg/mL) and PV (100 μg/mL) groups showed obvious activity. In terms of cardioprotective activity, the four kinds of lipid groups significantly increased the zebrafish heart rhythms. The heart distances were shortened, except for those of the FC (100 μg/mL) and PJ (25 μg/mL) groups. Our comprehensive lipidomics analysis and bioactivity study of lipids from different sources could provide a basis for the better utilization of shrimp. [ABSTRACT FROM AUTHOR]

We describe a practical synthesis of (+)-9a-epi-stemo�amide, which has been achieved in six steps from α,β-unsaturated γ-butyrolactone. The main features of the current approach include a DBU-catalyzed Michael addition of nitroalkane and a reductive lactamization of nitro esters. [ABSTRACT FROM AUTHOR]

A propylene oxide assisted base-free Sonogashira cross-coupling reaction has been developed. The unique feature of the current protocol has extended the scope of Sonogashira reaction to some base-sensitive substrates. [ABSTRACT FROM AUTHOR]

(-)-Aphanorphine methyl ether was synthesized in ten steps from commercially available (2S,4R)-4-hydroxyproline, �featuring the C-2 configuration inversion of an intermediate amide and intramolecular Friedel-Crafts reaction. The present work �constitutes a formal synthesis of unnatural (+)-aphanorphine. [ABSTRACT FROM AUTHOR]

In this study, BaCe0.9Er0.1O3−α was synthesized by a microemulsion method. Then, a BaCe0.9Er0.1O3−α–K2SO4–BaSO4 composite electrolyte was obtained by compounding it with a K2SO4–Li2SO4 solid solution. BaCe0.9Er0.1O3−α and BaCe0.9Er0.1O3−α–K2SO4–BaSO4 were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and Raman spectrometry. AC impedance spectroscopy was measured in a nitrogen atmosphere at 400–700 °C. The logσ~log (pO2) curves and fuel cell performances of BaCe0.9Er0.1O3−α and BaCe0.9Er0.1O3−α–K2SO4–BaSO4 were tested at 700 °C. The maximum output power density of BaCe0.9Er0.1O3−α–K2SO4–BaSO4 was 115.9 mW·cm−2 at 700 °C, which is ten times higher than that of BaCe0.9Er0.1O3−α. [ABSTRACT FROM AUTHOR]

The synthesis of pyrimidine‐spirofused indolines from 1,3,5‐triazinanes with 2‐sulfonyliminoindolines has been achieved under catalyst‐ and additive‐free conditions, in which five atoms of 1,3,5‐triazinanes were introduced to the spiro‐annulation products via a (5+1) pathway. Subsequently, this strategy was extended to 3‐aminoindoles and 3‐aminobenzothiophenes, but a different reaction pathway (3+3) was observed. In these cases, three‐atoms of 1,3,5‐triazinanes were incorporated into pyrimidine‐fused indoles/benzothiophenes. These two transformations demonstrate the potential and versatility of 1,3,5‐triazinanes to construct nitrogen‐heterocycles. [ABSTRACT FROM AUTHOR]

Comprehensive Summary: A metal‐free, green, and sustainable functionalization of unactivated alkyl sp3 C—H bonds is reported using iodine(III) as a feasible dehydrogenation agent under visible light or KBr, and alkyl chlorides, bromides, alcohols, and ketones could be constructed by addition of different coupling reagents. Cheap and safe iodobenzene diacetate was used to form a radical to activate the alkyl sp3 C—H bond in a highly efficient manner, which can construct different alkylation products by adding corresponding coupling reagents. [ABSTRACT FROM AUTHOR]

Carbenes are pivotal reactive intermediates for accessing a wide range of complex molecules, which are frequently used in chemical synthesis and medicinal advancement. We have developed a convenient approach to fluorenes from α‐biaryldiazoacetates via low‐energy blue light‐induced photochemical generation of a carbene intermediate, where the reaction took place at room temperature without any catalysts, bases, or oxidants in acetonitrile. The present catalyst‐free and operationally simple approach enables highly efficient annulation of α‐biaryldiazoacetates under mild reaction conditions. [ABSTRACT FROM AUTHOR]

In this study, Ce 0.8 Er 0.2 O 2-α was prepared via a microemulsion method. Then, Ce 0.8 Er 0.2 O 2-α powder was mixed with melted NaCl-KCl (1:1 mol ratio) at the weight ratio of 80%: 20% to obtain Ce 0.8 Er 0.2 O 2-α -KCl-NaCl at 750 °C. Ce 0.8 Er 0.2 O 2-α and Ce 0.8 Er 0.2 O 2-α -KCl-NaCl were characterized by thermogravimetry analysis and differential scanning calorimetry (TGA-DSC), Raman spectrometer, X-ray diffraction (XRD) and scanning electron microscope (SEM). The log (σT) ~ 1000 T-1 plots and fuel cell performances of Ce 0.8 Er 0.2 O 2-α and Ce 0.8 Er 0.2 O 2-α -KCl-NaCl were tested at 400–700 °C. The maximum output power density of Ce 0.8 Er 0.2 O 2-α -KCl-NaCl was 187 mW cm-2 at 700 °C which is six times greater than that of Ce 0.8 Er 0.2 O 2-α. [ABSTRACT FROM AUTHOR]

We have developed an asymmetric route to (-)-aphanorphine from O-Me-d-tyrosine methyl ester hydrochloride salt, available from d-tyrosine in four steps. The tricyclic framework of (-)-aphanorphine was assembled stereoselectively by intramolecular Friedel-Crafts reaction of the corresponding bicyclic precursor, which was in turn generated via ring-closing metathesis reaction. [ABSTRACT FROM AUTHOR]

The main protease (Mpro) of SARS‐CoV‐2 is a well‐characterized target for antiviral drug discovery. To date, most antiviral drug discovery efforts have focused on the S4–S1′ pocket of Mpro; however, it is still unclear whether the S1′–S3′ pocket per se can serve as a new site for drug discovery. In this study, the S1′–S3′ pocket of Mpro was found to differentially recognize viral peptidyl substrates. For instance, S3′ in Mpro strongly favors Phe or Trp, and S1′ favors Ala. The peptidyl inhibitor D‐4–77, which possesses an α‐bromoacetamide warhead, was discovered to be a promising inhibitor of Mpro, with an IC50 of 0.95 μM and an antiviral EC50 of 0.49 μM. The Mpro/inhibitor co‐crystal structure confirmed the binding mode of the inhibitor to the S1′–S3′ pocket and revealed a covalent mechanism. In addition, D‐4–77 functions as an immune protectant and suppresses SARS‐CoV‐2 Mpro‐induced antagonism of the host NF‐κB innate immune response. These findings indicate that the S1′–S3′ pocket of SARS‐CoV‐2 Mpro is druggable, and that inhibiting SARS‐CoV‐2 Mpro can simultaneously protect human innate immunity and inhibit virion assembly. [ABSTRACT FROM AUTHOR]

Abstract: Rhodium‐iminocarbenes that are derived from N‐sulfonyl‐1,2,3‐triazoles have become an important class of reactive species and useful intermediates in organic synthesis. Over the last several years, many practical and versatile approaches involving rhodium‐iminocarbene intermediates to synthetically challenging molecules (scaffolds) have been developed. This Minireview mainly summarizes the recent advance of rhodium‐iminocarbene involved reactions in the synthesis of natural products and their related scaffolds by the end of 2017. Several applications in important pharmaceuticals are documented as well. [ABSTRACT FROM AUTHOR]

An array of spiro[benzofuran-2,3′-pyrazol]-3-imines with diverse functional groups were readily assembled from aurone-derived azadienes and in - situ generated nitrilimines under mild conditions. The transformation was performed in a regio- and diastereoselective fashion, in which a synergetic [2+3] cycloaddition pathway was likely involved. This novel methodology has extended the synthetic application of aurone-derived azadienes as a kind of two-atom synthon. [ABSTRACT FROM AUTHOR]

The synthesis of 4‐(trifluoromethyl)‐2,3‐dihydrothiazoles from α‐enolic dithioesters and imidoyl sulfoxonium ylides has been achieved under thermal conditions. This transformation is catalyst‐free, additive‐free, and operationally simple, and it proceeds via a formal insertion of alkenyl S−H generated in situ from dithioesters into ylides followed by an intramolecular annulation. This approach further expands the synthetic application of two versatile sulfur‐containing building blocks of fluorinated imidoyl sulfoxonium ylides and α‐enolic dithioesters. [ABSTRACT FROM AUTHOR]